Add refract node (#1698)

Adding refract node to partner with the reflect node, with a similar named interface, and implementation as a nodegraph taken from the OSL spec.
AcademySoftwareFoundation · Feb 7, 2024 · a81ed0c · a81ed0c
1 parent cff9a7c
commit a81ed0c
Show file tree

Hide file tree

Showing 2 changed files with 72 additions and 0 deletions.
diff --git a/libraries/stdlib/stdlib_defs.mtlx b/libraries/stdlib/stdlib_defs.mtlx
@@ -2761,6 +2761,17 @@
     <output name="out" type="vector3" />
   </nodedef>
 
+  <!--
+    Node: <refract>
+    Compute the refraction vector given an incident vector, unit surface normal, and index of refraction.
+  -->
+  <nodedef name="ND_refract_vector3" node="refract" nodegroup="math" doc="Compute the refraction vector">
+    <input name="in" type="vector3" value="1.0, 0.0, 0.0" doc="Incident vector"  />
+    <input name="normal" type="vector3" defaultgeomprop="Nworld" doc="Surface normal" />
+    <input name="ior" type="float" value="1.0" doc="Index of refraction" />
+    <output name="out" type="vector3" />
+  </nodedef>
+
   <!-- ======================================================================== -->
   <!-- Adjustment nodes                                                         -->
   <!-- ======================================================================== -->

diff --git a/libraries/stdlib/stdlib_ng.mtlx b/libraries/stdlib/stdlib_ng.mtlx
@@ -2728,6 +2728,67 @@
     <output name="out" type="vector3" nodename="reflection_vector" />
   </nodegraph>
 
+  <!--
+    Node: <refract>
+    Compute the refraction vector given an incident vector, unit surface normal, and index of refraction.
+  -->
+  <nodegraph name="NG_refract_vector3" nodedef="ND_refract_vector3">
+    <dotproduct name="IdotN" type="float">
+      <input name="in1" type="vector3" interfacename="in"/>
+      <input name="in2" type="vector3" interfacename="normal"/>
+    </dotproduct>
+    <multiply name="IdotNsq" type="float">
+      <input name="in1" type="float" nodename="IdotN"/>
+      <input name="in2" type="float" nodename="IdotN"/>
+    </multiply>
+    <multiply name="iorsq" type="float">
+      <input name="in1" type="float" interfacename="ior"/>
+      <input name="in2" type="float" interfacename="ior"/>
+    </multiply>
+    <subtract name="one_IdotNsq" type="float">
+      <input name="in1" type="float" value="1.0"/>
+      <input name="in2" type="float" nodename="IdotNsq"/>
+    </subtract>
+    <multiply name="iorsq_one_IdotNsq" type="float">
+      <input name="in1" type="float" nodename="iorsq"/>
+      <input name="in2" type="float" nodename="one_IdotNsq"/>
+    </multiply>
+    <subtract name="k" type="float">
+      <input name="in1" type="float" value="1.0"/>
+      <input name="in2" type="float" nodename="iorsq_one_IdotNsq"/>
+    </subtract>
+    <multiply name="I_scaled" type="vector3">
+      <input name="in1" type="vector3" interfacename="in"/>
+      <input name="in2" type="float" interfacename="ior"/>
+    </multiply>
+    <sqrt name="sqrt_k" type="float">
+      <input name="in" type="float" nodename="k"/>
+    </sqrt>
+    <multiply name="ior_NdotI" type="float">
+      <input name="in1" type="float" interfacename="ior"/>
+      <input name="in2" type="float" nodename="IdotN"/>
+    </multiply>
+    <add name="ior_NdotI_sqrt_k" type="float">
+      <input name="in1" type="float" nodename="ior_NdotI"/>
+      <input name="in2" type="float" nodename="sqrt_k"/>
+    </add>
+    <multiply name="N_scaled" type="vector3">
+      <input name="in1" type="vector3" interfacename="normal"/>
+      <input name="in2" type="float" nodename="ior_NdotI_sqrt_k"/>
+    </multiply>
+    <subtract name="refract_dir" type="vector3">
+      <input name="in1" type="vector3" nodename="I_scaled"/>
+      <input name="in2" type="vector3" nodename="N_scaled"/>
+    </subtract>
+    <ifgreater name="result" type="vector3">
+      <input name="value1" type="float" value="0.0"/>
+      <input name="value2" type="float" nodename="k"/>
+      <input name="in1" type="vector3" value="0.0, 0.0, 0.0"/>
+      <input name="in2" type="vector3" nodename="refract_dir"/>
+    </ifgreater>
+    <output name="out" type="vector3" nodename="result"/>
+  </nodegraph>
+
   <!-- ======================================================================== -->
   <!-- Adjustment nodes                                                         -->
   <!-- ======================================================================== -->